Causative agent of spotted fever group rickettsiosis in Japan

Abstract

Since 1984, it has been known that spotted fever group rickettsiosis exists in Japan. We isolated three strains of the causative rickettsiae, designated Katayama, Misaka, and Abe, from patients with the disease and studied the characteristics of the isolates. Nude mice and cyclophosphamide-treated mice died after infection with the isolates. However, infected normal mice recovered and acquired immunity. Infected adult male guinea pigs had fever, a scrotal reaction, and seroconversion. The isolates propagated well in tissue-cultured Vero cells. Analysis by the cross-immunofluorescence antibody method showed that these isolates were closely related serologically. To reveal their immunological properties in detail, we produced 21 anti-Katayama monoclonal antibodies. Seven of these antibodies reacted with all representative strains of spotted fever group rickettsiae used in this study, and five others reacted only with the homologous strain, revealing that the Katayama strain has a strain-specific antigen(s) different from those of other spotted fever group rickettsiae. Moreover, these strain-specific antibodies also reacted with the Misaka and Abe strains. These results demonstrate that the causative agent of spotted fever group rickettsiosis in Japan is a new serotype of spotted fever group rickettsiae.

Seroepidemiology of Spotted Fever Group Rickettsiae in Small Field Rodents in Japan

“…The serological analysis revealed that the agent was a new species of SFG (17,19), which was named as Rickettsia japonica (18). The similar agent was also reported by Okada et al (7). Later, patients with the SFG infection have been found in the southwestern areas of Japan facing the Pacific Ocean, i.e., Tokushima and Kochi prefectures in Shikoku (1, 5,13,15), Miyazaki Prefecture in Kyushu (11,20), Chiba Prefecture in Honshu (2, 3), and Awaji Island of Hyogo Prefecture near Shikoku (4).…”

Detection of DNA of Causative Agent of Spotted Fever Group Rickettsiosis in Japan from the Patient's Blood Sample by Polymerase Chain Reaction

“…Uchida et al first isolated the causative rickettsia from a patient in Muroto-city, Kochi Prefecture, in 1986, characterized the Japanese strains, and designated it as Rickettsia japonica (12)(13)(14)(15). We isolated the Katayama and Abe strains in Anan-city and the Misaka strain on Awaji Island, Hyogo Prefecture, from patients, and studied their characteristics in detail as reported previously (2,4,5,8). Thereafter, we isolated the Kojima strain from a patient on Awaji Island in 1990, and demonstrated that it belonged to the Katayama serotype, using serotype-specific monoclonal antibodies (unpublished data).…”

Sensitivity of Polymerase Chain Reaction Assay for Rickettsia tsutsugamushi in Patients' Blood Samples

“…Three reference strains of R. tsutsugamushi (Gilliam, Karp and Kato) (17) and two prototype strains isolated from tsutsugamushi disease patients in Kyushu, Japan (20) (Irie and Hirano) were grown in BS-C-1 cells in RPMI 1640 medium supplemented with 10% fetal bovine serum in humidified air with 5% CO2 at 35 C (21). The Katayama strain of the spotted fever group rickettsia in Japan, grown in BS-C-1 cells (14), and Escherichia coli ( JM 109) were used as controls.…”